Homestead Exemption lost on a temporary move?

I have owned a house in Georgia for 5 years and have had the Homestead Exemption during this time. I am now temporarily renting an apartment in a neighboring state while finishing up an advanced degree (for a few months). I still own the house, with the intent of returning full-time after school is over, and no one else currently lives in the house. I recently received a letter from the Board of Assessors, stating that they had received notice of change of address from the Post Office and were lifting my Homestead Exemption.---Is there a way to have that reversed? If it is revoked this year and I am back in the house by January 1st of next year, can I reapply, and would that exemption then only apply to a NEW rate? Yikes!